Abstract: In order to study the damage fracture law of multi-fracture, based on statistical damage theory, a multi-fracture model with different density and inclination angle was established, the crack propagation process and stress-strain law of the multi-fracture were simulated numerically, and the mechanism of wing cracks, the critical length of wing cracks with multiple cracks were discussed. The damage process of wing cracks was explained based on the acoustic emission numerical simulation results. The results showed that wing cracks occurred at and near the tip of the prefabricated crack, shear cracks occurred in the middle of the crack, and the prefabricated cracks near the boundary of the model existed "boundary effect ". The peak strength of different crack density models decreased by 4.3%, 4.7% and 18.8% respectively. The percentage of peak strength increased by different fracture angles was 13.2%, 45.2% and 61.9% respectively. The influence of crack angle on peak strength of model was greater than that of crack density. The mechanism of wing crack of single fracture is discussed and the critical crack length of wing crack of multi-fracture connecting with each other is deduced. 

Key words: crack propagation, crack inclination, crack density, numerical simulation, acoustic emission

摘要： 为研究多裂隙的损伤断裂规律，基于统计损伤理论，建立了含不同密度及倾角的多裂隙模型，对多裂隙的裂纹扩展过程、应力-应变规律进行了数值模拟，讨论了拉伸裂纹产生机理、多裂纹的临界长度，并基于声发射数值模拟结果说明了裂纹的损伤过程，结果表明，拉伸裂纹在预制裂纹尖端及靠近尖端产生，剪切裂纹产生于裂纹中部，靠近模型边界的预制裂纹存在“边界效应”；不同裂纹密度模型的峰值强度分别降低4.3%、4.7%及18.8%，不同裂隙角度的增大对模型峰值强度提供的百分比分别为13.2%，45.2%及61.9%，裂隙角度对模型峰值强度的影响要大于裂纹密度；讨论了单裂隙拉伸裂纹的产生机理，对多裂隙拉伸裂纹相互贯通的临界裂纹长度进行了推导。

关键词: 裂纹扩展, 裂纹倾角, 裂纹密度, 数值模拟, 声发射